High temperature thermal cutting systems (e.g., plasma arc systems, laser cutting systems, etc.) can be used for cutting metallic materials. The high temperature thermal cutting systems can be automated for automatically cutting a metallic workpiece. FIG. 1 shows a known automated plasma arc system 90. The depicted plasma arc cutting system 90 includes a plasma arc torch 100, an associated power supply/gas supply 110, a remote high-frequency (RHF) console 120, a positioning apparatus 130, a cutting table 140, a torch height control 150, and a digital signal processor 160 (e.g., an associated computerized numeric controller (“CNC”)).
A user can place a workpiece on the cutting table 140 and mount the torch (e.g., a plasma arc torch 100) on a positioning apparatus 130. The positioning apparatus can provide relative motion between the tip of the torch and the workpiece to direct the plasma arc or a cutting laser along a processing path. The user can provide a start command to the digital signal processor 160 initiate the cutting process. As shown in FIG. 1, the digital signal processor 160 (e.g., CNC) accurately directs motion of the torch and/or the cutting table to enable the workpiece to be cut to a desired pattern. The digital signal processor 160 is in communication with the positioning apparatus 130. The positioning apparatus 130 uses signals from the digital signal processor 160 to direct the torch 100 along a desired cutting path. Position information is returned from the positioning apparatus 130 to the digital signal processor 160 to allow the digital signal processor 160 to operate interactively with the positioning apparatus 130 to obtain an accurate cut path.
The torch 100 for a plasma arc system 90 generally includes a torch body, an electrode mounted within the body, passages for cooling fluid and cut and shield gases, a swirl ring to control the fluid flow patterns, a nozzle with a central exit orifice, and electrical connections (not shown). A shield can also be provided around the nozzle to protect the nozzle and to provide a shield gas flow to the area proximate the plasma arc. Gases applied to the torch can be non-reactive (e.g., argon or nitrogen) or reactive (e.g., oxygen or air).
Referring to FIG. 1, the tip of the torch 100 during operation can be positioned proximate the workpiece by the positioning apparatus 130. A pilot arc is generated between the electrode (cathode) and the nozzle (anode) by using, for example, a high frequency, high voltage signal from the RHF console. The pilot arc ionizes gas from the gas console passing through the nozzle exit orifice. As the ionized gas reduces the electrical resistance between the electrode and the workpiece, the arc transfers from the nozzle to the workpiece (e.g., transferred plasma arc mode). The transferred plasma arc mode is characterized by a conductive flow of ionized gas from the electrode to the workpiece, thereby cutting the workpiece.
The digital signal processor 160 (e.g., computer numerical controller) can be configured to operate with a plasma arc, laser, oxy fuel, and/or water jet technologies. The digital signal processor 160 allows the user (e.g., an operator of the automated high temperature thermal cutting system) to manually configure a large number of operating parameters.